Apparatus for tapering flexible metal tubes

ABSTRACT

Apparatus for converting flexible metal cylindrical tubes into nestable tapered tubes including a mandrel having a cylindrical portion shorter than the tube and a frustoconical portion whose largest diameter is equal to or greater than the filling opening of the tube and in which air is blown through ducts in the mandrel to force the tube against the inner surface of a matrix while the mandrel advances and the frusto-conical portion compensates for the widening of the bottom opening and the shortening of the length of the tube.

[4 1 Oct. 17,1972

United States Patent Couland 12/1954 Demarest..........,...........

Peccerrll [54] APPARATUS FOR TAPERING FLEXIBLE METAL TUBES [72] Inventor:

Roger Couland, Fontenay-aux- 3,151 Garvin...........................72/61 .29/421 Hutchins Roses, France Pesak [73] Assignee: Societe de Conditionement en Aluminum, Paris, France June 22, 1971 Primary Examiner-Richard J. Herbst Attorney-McDougall, Hersh & Scott [22 Filed:

Appl. No.: 155,540

[5 7] ABSTRACT Apparatus for converting flexible metal cylindrical tubes into nestable tapered tubes including a mandrel France......................7023778 having a cylindrical portion shorter than the tube and US. a frustoconical portion whose largest diameter is equal [51] Int. Cl. 26/04 to or greater than the filling opening of the tube and in .72/57, 58, 60, 61, 62, 63, 72/367, 56, 370; 29/421, DIG. 41

[58] Field Search-mm" which air is blown through ducts in the mandrel to force the tube against the inner surface of a matrix 56 R f d while the mandrel advances and the frusto-conical 1 e erences portion compensates for the widening of the bottom UNITED STATES PATENTS opening and the shortening of the length of the tube.

...72/56 10 Claims, 1 Drawing Figure 2,038,304 4/1936 Middler......

APPARATUS FOR TAPERING FLEXIBLE METAL TUBES This invention relates to a machine intended to impart a conical shape to flexible metal tubes originally of cylindrical shape. The transformation enables the formed tubes to nest one within the other.

This is an improvement over my copending application Ser. No. 15,735, filed Mar. 2, 1970, and titled Apparatus for Tapering Flexible Tubes.

In the aforementioned copending application, description is made of an apparatus in which the tube to be tapered is fitted onto a support, the opening at its lower end being placed on a slidable conical sleeve. The tube is covered by a matrix and, by means of air blown inside, it is pressed against the matrix. At the same time, the sleeve advances at a rate proportional to that at which the opening at the lower end widens and the length of the tube decreases. In the described machine, the male portion comprises two sections, namely the mandrel and the sleeve slidably mounted thereon. These two sections had to be adjusted with great precision one on the other and the advance of the sleeve involved extremely careful regulation.

The machine of this invention enables the desired results to be obtained more uniformly and more rapidly.

In accordance with the practice of this invention, the cylindrical metal tube is placed on a mandrel inside a conical matrix and expanded to the desired shape by blowing air under high pressure through the mandrel. The mandrel comprises a cylindrical part which is dimensioned to have a length less than the cylindrical tube, followed by a widening frustoconical part having a length at least equal to the difference between the length of the cylindrical part of the mandrel and the overall length of the tube. The diameter of the major base of the frustoconical part of the mandrel is at least equal to the largest diameter of the widened tube. The cylindrical part of the mandrel is formed with openings extending therethrough which communicate with the source of high pressure air through the mandrel.

The accompanying drawing diagrammatically illustrates the machine embodying the features of this invention for tapering cylindrical tubes. That portion of the drawing to the left of the line X-Y illustrates the arrangement of parts at the beginning of the operation, while that part of the drawing to the right of the line X-Y illustrates the arrangement upon completion of the operation.

As illustrated in the drawing, a support A carries two members which are employed for the tapering of cylindrical tubes, namely the matrix 11 and the mandrel 20.

The matrix 11 is formed with passages 12 which extend radially through the side walls. Its interior or cavity is of frustoconical shape and corresponds to the shape which the tube is intended to assume.

The mandrel 20 enters the matrix through the open end 13 in which the diameter of the opening is at least equal to the largest diameter of the tapered tube. The opposite end of the matrix 11 has a smaller opening dimensioned to receive the stopper 1" which caps the tube, as by threaded engagement with the threaded end 14" of the tube.

Themandrel 20 is formed with four zones, namely part 21, preferably of cylindrical shape, having a diameter equal to or slightly less than the internal diameter of the cylindrical tube to be tapered and a length less than that of the tube.

The upper free end 22 of the part 21 is formed to frustoconical shape, which corresponds to the internal shape of the shoulder of the tube. On the other end of the cylindrical part 21, the mandrel tapers outwardly to form a short frustoconical part 23 whose largest diameter is at least equal to that of the filling opening at the lower end of the tapered tube. Finally, the mandrel terminates in an end part 24 designed to enable it to be fixed or connected to a rod 50 which is mounted for linear reciprocatory movement in response to actuation by a jack 52, hydraulic cylinder, or other equivalent reciprocating mechanism.

The mandrel 20 is formed with a central duct 30 which extends therethrough. In its cylindrical part 21, the mandrel is formed with a plurality of passages 31 which extend therethrough to communicate the duct with the exterior of the mandrel. The duct 30 is connected to a source of compressed. air through the hollow rod 50.

The machine operates as follows:

The cylindrical tube 1 is manually or preferably automatically placed on the cylindrical part 21 of the mandrel 20 with its free lower edge touching the beginning of the frustoconical part 23, as illustrated to the left of the line X-Y in the drawing. There is thus left between the free end 22 of the mandrel and the shoulder 1" of the tube an empty space 25, the height H of which is equal to or less than the height H, of the frustoconical part 23 of the mandrel.

The mandrel 20, covered by the tube 1, is advanced into the matrix by the rod 50, operated by the jack 52, until the shoulder 1' of the tube comes into contact with the corresponding end of the matrix while the previously applied stopper 1" extends through the opening 14 which has been provided for this purpose.

Thereafter, compressed air is introduced through the hollow rod 50 to the duct 30 for distribution through the openings 31 which extend through the mandrel. Air pressure is thus applied to the inner wall of the tube 1 which is thus inflated over its entire length. During inflation, the mandrel 20 is advanced further into the tube with its conical part constantly remaining in contact with the rim of the filling opening of the tube, which widens progressively. In this way, the air blown into the tube is confined between the wall of the tube and the mandrel whereby the tube is pressed progressively against the matrix 11. The air which is in the area between the tube 1 and the matrix 11 is allowed to escape through the openings 12 in the matrix. When the tip 22 of the mandrel engages the inside of the shoulder 1" of the tube, the tapering operation is completed. After completion of the operation, the mandrel 20, with the deformed tube thereon, is withdrawn from the matrix and the tube is separated from the mandrel by blowing a gentle stream of air through the duct 30. The tapered tubes can now be stacked by nesting one within the other.

It will be apparent from the foregoing that I have provided a simple and efficient means for converting cylindrical tubes into slightly tapered "tubes which can be stacked one upon the other. It will be understood that changes may be made in the details of construction and operation without departing from the spirit of the invention, especially as defined in the following claims.

lclaim:

1. In an apparatus for tapering tubes of cylindrical shape comprising a matrix having an interior cavity of conical shape, and a mandrel mounted for reciprocal movement relative to the matrix within said cavity between advanced and retracted positions, said mandrel having an end portion of cylindrical shape dimensioned to have a length less than the length of the cylindrical tube, a tapered portion of frustoconical shape dimensioned to have a length at least equal to the difference between the length of the cylindrical portion and the length of the tube, means communicating the exterior of the cylindrical portion of the mandrel with a source of fluid under pressure for blowing the tube when positioned thereon for expanding the tube against the matrix, and means for actuation of the mandrel between advanced and retracted positions.

2. An apparatus as claimed in claim 1 in which the tube is a flexible metal tube.

3. An apparatus as claimed in claim 1 in which the cylindrical portion of the mandrel is dimensioned to have a length greater than the length of the frustoconical portion.

4. An apparatus as claimed in claim 1 in which the fluid under pressure is compressed air.

5. An apparatus as claimed in claim 1 in which the diameter of the major base of the frustoconical portion is at least equal to the largest diameter of the tapered tube.

6. An apparatus as claimed in claim 1 in which the diameter of the major base of the frustoconical portion is at least equal to the widest portion of the conically shaped cavity less the wall thickness of the tube.

7. An apparatus as claimed in claim 1 in which the means communicating the exterior of the cylindrical portion of the mandrel with a source of fluid under pressure comprises passages through the wall of the cylindrical portion of the mandrel and means comm unicating said passages with a source of fluid under pressure.

8. An apparatus as claimed in claim 7 which includes a passage extending axially through the mandrel into communication with the openings through the cylindrical portion and means communicating the passage with the source of fluid under pressure.

9. An apparatus as claimed in claim 1 in which the mandrel is mounted for linear movement between advanced and retracted positions and the means for actuation of the mandrel in reciprocal movement between extended and retracted positions comprises a connecting rod and a jack operatively connected to the rod for reciprocal movement.

10. An apparatus as claimed in claim 9 in which the rod has a passage extending therethrough and in which the means communicating the exterior of the cylindrical portion of the mandrel with the source of fluid under pressure comprises a passage through the mandrel in communication with the passage through the rod, openings through the cylindrical portion of the mandrel in communication with the passage therethrough and means communicating the passage in the rod with the source of fluid under pressure. 

1. In an apparatus for tapering tubes of cylindrical shape comprising a matrix having an interior cavity of conical shape, and a mandrel mounted for reciprocal movement relative to the matrix within said cavity between advanced and retracted positions, said mandrel having an end portion of cylindrical shape dimensioned to have a length less than the length of the cylindrical tube, a tapered portion of frustoconical shape dimensioned to have a length at least equal to the difference between the length of the cylindrical portion and the length of the tube, means communicating the exterior of the cylindrical portion of the mandrel with a source of fluid under pressure for blowing the tube when positioned thereon for expanding the tube against the matrix, and means for actuation of the mandrel between advanced and retracted positions.
 2. An apparatus as claimed in claim 1 in which the tube is a flexible metal tube.
 3. An apparatus as claimed in claim 1 in which the cylindrical portion of the mandrel is dimensioned to have a length greater than the length of the frustoconical portion.
 4. An apparatus as claimed in claim 1 in which the fluid under pressure is compressed air.
 5. An apparatus as claimed in claim 1 in which the diameter of the major base of the frustoconical portion is at least equal to the largest diameter of the tapered tube.
 6. An apparatus as claimed in claim 1 in which the diameter of the major base of the frustoconical portion is at least equal to the widest portion of the conically shaped cavity less the wall thickness of the tube.
 7. An apparatus as claimed in claim 1 in which the means communicating the exterior of the cylindrical portion of the mandrel with a source of fluid under pressure comprises passages through the wall of the cylindrical portion of the mandrel and means communicating said passages with a source of fluid under pressure.
 8. An apparatus as claimed in claim 7 which includes a passage extending axially through the mandrel into communication with the openings through the cylindrical portion and means communicating the passage with the source of fluid under pressure.
 9. An apparatus as claimed in claim 1 in which the mandrel is mounted for linear movement between advanced and retracted positions and the means for actuation of the mandrel in reciprocal movement between extended and retracted positions comprises a connecting rod and a jack operatively connected to the rod for reciprocal movement.
 10. An apparatus as claimed in claim 9 in which the rod has a passage extending therethrough and in which the means communicating the exterior of the cylindrical portion of the mandrel with the source of fluid under pressure comprises a passage through the mandrel in communication with the passage through the rod, openings through the cylindrical portion of the mandrel in communication with the passage therethrough and means communicating the passage in the rod with the source of fluid under pressure. 